Equipment ratings for the four-bus power system shown in

Chapter , Problem 7.12

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Equipment ratings for the four-bus power system shown in Figure 7.14 are as follows: Generator G1: 500 MVA, 13.8 kV, X00 _ 0:20 per unit Generator G2: 750 MVA, 18 kV, X00 _ 0:18 per unit Generator G3: 1000 MVA, 20 kV, X00 _ 0:17 per unit Transformer T1: 500 MVA, 13.8 D/500 Y kV, X _ 0:12 per unit Transformer T2: 750 MVA, 18 D/500 Y kV, X _ 0:10 per unit Transformer T3: 1000 MVA, 20 D/500 Y kV, X _ 0:10 per unit Each 500-kV line: X1 _ 50 W A three-phase short circuit occurs at bus 1, where the prefault voltage is 525 kV. Prefault load current is neglected. Draw the positive-sequence reactance diagram in per-unit on a 1000-MVA, 20-kV base in the zone of generator G3. Determine (a) theThevenin reactance in per-unit at the fault, (b) the subtransient fault current in perunit and in kA rms, and (c) contributions to the fault current from generator G1 and from line 12.